The present disclosure relates to a communication device, a communication system and a communication method, and, particularly, to a communication device, a communication system and a communication method capable of wireless communication in close proximity.
When transferring data between small information devices, a method of communicating data through interconnection between information devices by use of a general-purpose cable such as a USB cable or a method of transferring data via a medium such as a memory card is generally adopted.
In recent years, cases of using a wireless interface, in place of such methods, have been on the increase. Concurrently, information devices incorporating various cable-less communication functions are provided. As a method of performing data communication in a cable-less manner between small information devices, radio frequency communication that transmits and receives radio signals using antennas, including wireless LAN typified by IEEE802.11 and Bluetooth (registered trademark) communication, is developed. The radio frequency communication eliminates the need to insert and withdraw a connector and route a cable at each data communication when exchanging data such as images or music, thus offering enhanced user-friendliness.
Further, a close proximity wireless communication system that uses a high frequency coupler rather than an antenna and achieves wireless communication in a short distance of several centimeters utilizing electric field coupling by an electrostatic field or an induction field has been proposed (cf. e.g. Japanese Patent No. 4345849). In the close proximity wireless communication system, a communication distance is as short as several centimeters to prevent crosstalk with wireless LAN, Bluetooth (registered trademark) communication or the like. Therefore, the close proximity wireless communication system enables broadband communication without interference with another communication system. Further, the close proximity wireless communication system enables high-speed data transfer, thus allowing transfer of high-volume data in a short time, such as transfer of digital camera images or transfer of digital video camera high-definition pictures.